Isocitrate dehydrogenase 2 deficiency exacerbates dermis damage by ultraviolet-B via ΔNp63 downregulation

Isocitrate dehydrogenase 2 (IDH2) is a key enzyme that maintains the balance of mitochondrial redox status by generating NADPH as a reducing factor, which is used to reduce oxidized antioxidant proteins and oxidized glutathione. Therefore, the role of IDH2 is crucial in organs that are easily influenced by reactive oxygen species (ROS) or mechanical damage. Humans are constantly exposed to ultraviolet (UV) radiation throughout their lifetime, which can cause various cutaneous diseases, such skin carcinoma, dermatitis, and sunburn. ROS play an important role in the initial step of these diseases; therefore, IDH2 deficient mice (Idh2^-/-) could be a useful model to investigate UV-mediated skin damage. When we exposed the dorsal skin of Idh2^-/- mice to UVB, pyrimidine dimers and (6-4) photoproducts (6-4PPs), marker of photoproducts generated by UVB, were found in the dermis of the knockout mice. Increased collagen degradation, apoptosis, inflammation, and ROS levels in the dermis were also observed. These results indicated that UVB could reach the dermis by penetrating the epidermis. We then attempted to determine how the epidermis was breached, and observed a decrease in the expression level of ΔNp63, a major protein required for epidermis generation, in the Idh2^-/- mice. The mito-TEMPO supplement significantly ameliorates UVB-induced damage in the skin of Idh2^-/- mice. In the present study, we provided a role for IDH2 in protection against UVB-induced skin damage and a new connection between IDH2 and ΔNp63.